By Dr. Diedre Rippl
Beaver Dam Community Hospital
Since 1989, death rates from breast cancer have been declining as a result of new technological advancements in early detection and improved diagnostic accuracy of staging.
Early detection starts with superior screening mammography or low-dose X-rays. Originally, film screen or conventional mammography was used. It was replaced by full field digital mammography when it was approved by the FDA to replace conventional mammography in 2000.
Digital mammography allows the interpreting radiologist to manipulate the images by magnifying or adjusting the contrast to gather more diagnostic information. It has been proven that detection rates for digital mammography are far superior to conventional mammography and have decreased the rate of false positive results.
Although digital mammography is excellent and has been proven to decrease mortality rates, interpreting radiologists can still be faced with a dilemma – breast overlap or superimposition of breast tissue. This is a particular problem in women with dense breast tissue (the density of breast tissue is not a major risk factor for breast cancer, although the sensitivity of detection in dense breasts can drop).
It is impossible to position the breasts in the exact same position from year to year during screening mammograms, and when the positioning has changed, overlap can occur. This superimposition could possibly obscure visualization of a cancer. For this reason, researchers have developed a new and promising imaging modality called breast tomosynthesis, the next generation of digital mammography.
Breast tomosynthesis, or 3D mammography, is a new advancement that is similar to other modalities such as CT, but with a radiation dose similar to that used with routine mammography. The breast is compressed just enough to hold it in place and reduce patient motion. This is far different from routine mammography where it is necessary to apply a lot of compression to achieve tissue uniformity.
Once the patient is positioned, the mammography X-ray tube moves in an arc above the breast or on the side of the breast, acquiring images or slices at different angles in a rapid sequence. After acquisition of the images, they are digitally reconstructed and can be viewed as a 3-dimensional image as compared to two dimensions with routine mammography. This greatly reduces tissue overlap and increases the cancer detection rate while decreasing false positive results.
Breast MRI is another advanced modality for breast screening in high-risk individuals (BRCA gene positive or strong family history). It has been shown to greatly increase the rate of cancer detection. Screening MRI is now recommended by the American Cancer Society for any individual who is at high risk, or has a greater than 20 percent lifetime risk of developing breast cancer.
These high-risk individuals should alternate every six months between screening mammography and screening MRIs every year. It should be noted that screening breast MRI complements mammography, but does not replace annual mammography.
Breast MRI also plays a role in breast care management. It is useful in evaluating benign lesions or other conditions such as the integrity of breast implants. It is also valuable in staging of breast cancer. After a diagnosis is made, breast MRI can be useful in evaluating the tumor (size) and the surrounding tissues (soft tissue invasion, lymph nodes) to aid in accurate diagnostic staging and future management.
Breast cancer is the most common cancer among American women. Early detection of breast cancer is the key to increased survival. Each woman should take personal responsibility and perform monthly self-examinations. This in conjunction with a yearly breast examination by a physician and annual mammography and/or tomosynthesis in women age 40 and older is the first step to detection. In high risk individuals, advanced modalities such as breast MRI may be warranted.
Dr. Diedre Rippl was fellowship trained at the University of Texas MD Anderson Center with a musculoskeletal subspecialty and works with Beaver Dam Community Hospitals, Inc. To schedule a mammogram, please call (920) 887-4006.
